JP3477173B2 - Photosensitive material using microcapsules - Google Patents

Description

Detailed Description of the Invention

TECHNICAL FIELD The present invention relates to improvements in photosensitive imaging systems of the type taught in US Pat. Nos. 4,399,209 and 4,440,846 which utilize highly opaque backing layers in the photosensitive material.

BACKGROUND OF THE INVENTION Imaging systems using microencapsulated radiation-sensitive compositions are described in US Pat. No. 4,399,209; 4.4.
16,966; 4,440,846; 4,766,050 and 5,78
Subject to No. 3,353. These imaging systems are characterized by the image-wise exposure of an imageable sheet comprising a layer of microcapsules containing a photocurable composition in the internal phase to actinic radiation. In the most typical embodiment, the photocurable composition is a photopolymerizable composition containing a polyethylenically unsaturated compound and a photoinitiator, and the color former is encapsulated by the photopolymerizable composition. There is. The exposure to actinic radiation cures the internal phase within the microcapsules. After exposure, the imageable sheet is developed by subjecting it to a uniform destructive force in the presence of a developer. Image transfer systems, i.e. copy sheets, in which a developer material is coated as a separate developer on a separate substrate are disclosed in U.S. Pat. No. 4,399,209. Self-contained imaging systems in which the encapsulated color former and developer material are present in one layer or two interactive layers are described in US Pat.
No. 440,846.

Imaging systems, especially US Pat. No. 4,440,846.
When exposing and developing self-contained imaging systems of the type described in U.S. Pat. No. 5,783,353 in small format printers, these systems often expose the imageable sheets in an overlapping state. If desirable. To do so, it is important that the exposing light is not transmitted through the overlying upper imageable sheet to the underlying sheet, or the underlying sheet may deteriorate. In addition, there are certain applications in which it may be desirable to write or print on the back side of the image. It is important that this printing does not show through the support and does not degrade the image quality.

DISCLOSURE OF THE INVENTION According to the present invention, a layer of photosensitive microcapsules; and a first film containing a white pigment, a second film containing a black pigment and a third film containing a white pigment. In the simplest form, a photosensitive material containing a support which is a laminate of the above is provided. In a more detailed embodiment of the present invention, the photosensitive material comprises a layer of photosensitive microcapsules, a developer in the same layer as the microcapsules or in a separate layer, and an opaque support having a laminate structure as described above. It is a self-contained photosensitive material containing In another embodiment of the invention, there is provided a digital printer medium that can be imaged on both sides of one medium. The imageable material comprises a pair of transparent supports (e.g. PET) located outside the mixture layer of photosensitive microcapsules and developer or the individual layers of microcapsules and developer.
including. In the middle of the imageable material is the opaque structure described above.

US Pat. Nos. 4,399,209; 4,440,846 and 5,783,353 are incorporated by reference to the extent not inconsistent with the teachings herein. The improved imaging system of this invention has the light-sensitive microcapsules and developer material co-deposited in one layer or two interactive layers as described in U.S. Pat.No. 5,783,353. Can be embodied in a self-contained copy sheet; or
The imaging system of the present invention is described in U.S. Pat.No. 4,399,209 in which the photosensitive microcapsules and the developer material are coated on separate substrates and the microcapsules are exposed to form a latent image and then assembled. It can be embodied in a transfer system as described. The imaging system of the present invention also includes a two-sided self-contained system in which the microcapsules and the developer are used in one layer or individual layers exactly as described above on opposite sides of an opaque support. Can be embodied in. Each system operates by photographic access control between the color forming material and the developer as described above. In self-contained imaging systems, the chromogenic material and the developer can react to form a visible image in the unexposed areas after the capsule is broken. Gradual development of the visible image is observed as the chromogenic material leaches out of the microcapsules, transfers to the developer, mixes and reacts after exposure and capsule destruction. In the most typical embodiment, encapsulation is disrupted by pressing the imageable sheet alone (for self-contained systems) or by contact with the developer sheet using pressure rolls or roller balls (transfer system). In the case of). In order to record an image, the image forming material is used.
Scan with the LED print head and develop by applying pressure to this unit. The media can be imaged using a printer containing an LED / developer head of the type described in US Pat. No. 5,550,627.

In accordance with the present invention, the photosensitive material described above is constructed with a highly opaque support that allows the material to be overexposed or printed on the backside without image degradation. To do. This support is a laminate of an opaque black film between two opaque colored white films. This support is available from DuPont under the trade name Melinex.
Available commercially as (Melinex) 6295. The support is typically about 4 mils thick, about 1/3 of the thickness comes from each individual film. The white pigment is typically barium sulphate, but those skilled in the art
It will be appreciated that other white pigments can be used. The dark pigment is carbon black. However, in another embodiment of the invention, iron oxide of the type used in conventional magnetic recording films and
/ Or use chromium oxide as a dark pigment in the intermediate laminate film. In this way, the information can be magnetically recorded in the film, thereby making the photosensitive material of the present invention usable in certain information and / or security applications. For example, the light-sensitive material of the present invention can be an employee identification badge that includes a photograph of the employee in a badge and magnetically records information about the employee in the film, or some type of code on the film. Magnetic recording inside,
Imprinting a film containing the photosensitive material of the present invention on a suitable reader may allow for employee acceptance into a place of employment or a restricted area within the place of employment.

A photosensitive material according to one embodiment of the present invention is illustrated in more detail in FIG. Self-contained system 1
Is a first transparent support 10, a subbing layer (undercoat layer) 11, an imageable composition 12 containing photocurable microcapsules 14 and a developer substance 16, an adhesive layer 18, and an opaque support 20 in that order. Including. Image-forming layer 12 is about 20-80% (dry weight) developer,
About 80-20% (dry weight) microcapsules and 0-20
% Binder is typically included. This layer is about 8-2
It is typically applied at a dry coating weight of 0 g / cm ² .
Examples of such coating formulations are illustrated in later examples.

The image is in accordance with the invention US Pat.
Formed in the same manner as described in No. 846. Imagewise exposing the unit to actinic radiation specifically cures the microcapsules within the exposed areas. The exposed unit is pressurized to destroy the microcapsules. FIG. 2 shows the self-contained imaging system of FIG. 1 after exposure and destruction of microcapsules 14. The destroyed microcapsules 22 release a color former, at which time the developer material 16 reacts with the color former to form an image.
Forming 24. The image formed is viewed through transparent support 10 against support 20. The support 20 is a three layer structure comprised of two outer white pigmented coloring films 30, 32 of a white pigment such as barium sulfate and an inner black or brown pigmented coloring film or coating 34, as illustrated in FIG. 1A. Is. Each film can be a coextruded PET film, or the white film can be coated with a pigmented layer (eg, a magnetic recording layer) and heat sealed with another white film to form a laminate. The transparent image-bearing support may be formed from any transparent polymeric film. Select a film that gives good photographic quality when viewing the image. Preferably, a film resistant to yellowing and containing a UV absorber is used. A preferred substrate is polyethylene terephthalate (PET), a transparent polymeric material. Typically, PET is about 25.4-101.6μ
It has a thickness of m (1 to 4 mils).

FIGS. 3 and 4 illustrate a further embodiment in which a developer is used in layer 16 'and microcapsules in layer 14' instead of the single layer of FIGS. As will be described later, this assembly sequentially coats the support 10 with a subbing layer 11, a developer layer 16 'and a microcapsule layer 14', and the assembly is coated with an opaque film 20.
It can be manufactured by fixing with a pressure sensitive adhesive 18. When this unit is exposed and the capsule is destroyed, the image
24 'is formed in layer 16'.

FIG. 5 illustrates a further embodiment of the photosensitive material according to the present invention. This photosensitive material has the reference numeral 11
And first and second transparent films 12 and 1 provided generally by subbing layers 16 and 18, respectively.
4, and photosensitive microcapsules 24 and developer material 2
Includes 6 mixing layers 20 and 22. These films are fixed to an opaque support 27. Each microcapsule carrying film is fixed to the opaque film 27 by a pair of adhesive layers 28 and 30. To make this unit, the microcapsules and developer in mixed or separate layers can be coated on transparent PET. The coated film is then laminated with an opaque film coated with adhesive on one or both sides. A subbing layer is preferably used on the transparent PET film to firmly bond the films together so that the films cannot be separated without unit degradation. Of course, other manufacturing methods can be used. In the manufacture of a two-sided unit to adhesive backed unit, an opaque film is coated on both sides with an adhesive. The adhesive backing unit is covered with a release liner on one side. The two-sided unit is attached to the microcapsule film.

The operating center of the imaging system of the present invention is the internal phase of the encapsulation or microcapsules. According to the invention, this internal phase comprises the photosensitive composition and the chromophoric substance. Typically, the photosensitive composition comprises a photoinitiator and a substance that undergoes a viscosity change upon exposure in the presence of the photoinitiator. The material is most typically a monomer, dimer or oligomer that polymerizes to a high molecular weight compound, or can be a crosslinkable polymer. If a negative working imaging element is desired, the material can be a compound that depolymerizes or decomposes upon exposure.

Typically, the photosensitive composition is a free radical addition-polymerizable or crosslinkable composition. The most typical examples of free radical addition-polymerizable or crosslinkable compositions useful in the present invention are ethylenically unsaturated compounds,
More specifically, it contains a polyethylene unsaturated compound. These compounds include both monomers with one or more ethylenically unsaturated groups such as vinyl or allyl groups, and polymers with terminal or pendant ethylenic unsaturation. Such compounds are well known in the art and include acrylic or methacrylic esters of polyhydric alcohols such as trimethylolpropane, pentaerythritol and the like; and acrylate or methacrylate terminated epoxy resins, acrylate or methacrylate terminated polyesters and the like. . As a typical example, ethylene glycol diacrylate,
There are ethylene glycol dimethacrylate, trimethylolpropane triacrylate (TMPTA), pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, dipentaerythritol hydroxypentaacrylate (DPHPA), hexanediol-1,6-dimethacrylate, and diethylene glycol dimethacrylate. . Other radiation curable and radiation depolymerizable materials are described in US Pat. No. 4,399,209.

The color-forming substance used in the present invention includes the color-forming substance normally used in carbon-free paper. Generally, these materials are colorless electron-donor dye precursor compounds that react with a developer compound to form a dye. Representative examples of such dye precursors are substantially colorless compounds having a lactone, lactam, sultone, spiropyran, ester or amide structure in their backbone. Inter alia triarylmethane compounds,
There are bisphenylmethane compounds, xanthene compounds, thiazine compounds, spiropyran compounds and the like. Typical of these compounds are crystal violet lactone, benzoyl leuco methylene blue, malachite green lactone, p-nitrobenzoyl leuco methylene blue, 3-dialkylamino-7-dialkylamino-fluorane, 3-methyl-2,2'-spirobine. (Benzo-f-chromium), 3,3-
Bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2 -Methylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-phenylindol-3-yl) phthalide, 3,3-bis (1,2-dimethylindol-3-yl) ) -5-Dimethylaminophthalide, 3,3-bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl)- 5-dimethylaminophthalide, 3,3-bis (2-phenylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1-methylpyrrol-2-yl) -6-dimethylamino Phthalide, 3-p-dimethylaminophenyl-3- (1-methylpyrrol-2-yl) -6-dimylaminophthalide, 4,4'-bis-dimethylaminobenzhydrin benzyl ether, N-halofe Le leucoauramine,
N-2,4,5-trichlorophenyl leuco auramine, rhodamine-B-anilinolactam, rhodamine- (p-nitroanilino) lactam, rhodamine-B- (p-chloroanilino) lactam, 3-dimethylamino-6-methoxy Fluorane, 3-diethylamino-7-methoxyfluorane, 3-diethylamino-7-chloro-6-methylfluorane, 3-diethylamino-6
-Methyl-7-anilinofluorane, 3-diethylamino-7-
(Acetylmethylamino) fluorane, 3-diethylamino
-7- (dibenzylamino) fluorane, 3-diethylamino-
7- (methylbenzylamino) fluorane, 3-diethylamino-7- (chloroethylmethylamino) fluorane, 3-diethylamino-7- (diethylamino) fluorane, 3-methyl-
Examples include spiro-dinaphthopyran, 3,3′-dichloro-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho- (3-methoxybenzo) -spiropyran, 3-propyl-spirodibenzodipyran. Mixtures of these dye precursors can also be used if desired. Also,
The fluoran color forming agents disclosed in US Pat. No. 3,920,510 are also useful in the present invention.

According to the present invention, the color forming substance is contained in the internal phase in an amount sufficient to produce a desired density visible image upon reaction with the developer. Generally, these amounts range from about 0.5 to about 20.0% by weight of the internal phase containing chromogen (eg, monomers, oils and other additives). The preferred range is about 2 to about 8%. The amount of chromogenic material needed to obtain the proper image depends on the nature of the chromogen,
It depends on the nature of the internal phase and the type of imaging system. Smaller amounts of chromogenic material can be used in the internal phase of the self-contained imaging system in which the developer material is co-deposited with the microcapsules on a common substrate. To prevent unwanted coloration in self-contained sheets, color inhibitors can be mixed with the color forming material.

In addition to the color-forming substance and the light-sensitive substance, the internal phase of the microcapsules may also contain a carrier oil which influences and controls the tonality of the resulting image. Color tone
(Halftone gradation) is an important factor in a pictorial image with accurate reproducibility. Earlier studies have disclosed that when trimethylolpropane is used in a radiation curable material, a carrier oil such as 20% brominated paraffin can improve tonal quality. Preferred carrier oils are weakly polar solvents with boiling points above 170 ° C, preferably in the range 180 ° C to 300 ° C. The carrier oil used in the present invention is typically an oil commonly used in carbon-free paper production. These oils generally contain 0.5% crystal violet lactone.
It is characterized by its ability to dissolve at a concentration of not less than mass%. However, carrier oil is not necessary. Whether a carrier oil should be used depends on the solubility of the chromophoric substance in the photosensitive composition before exposure, the nature of the chromophoric substance, and the viscosity of the internal phase properties. Examples of carrier oils, when present, are alkylated biphenyls (e.g., monoisopropyl biphenyl), polychlorinated biphenyls,
Castor oil, mineral oil, deodorized kerosene, naphthenic mineral oil, dibutyl phthalate, dibutyl fumarate, brominated paraffin and mixtures thereof. Alkylated biphenyls are generally preferred due to their low toxicity.

Various photoinitiators can be used in the present invention. These compounds absorb exposure radiation and generate free radicals, alone or in combination with photosensitizers. Normal,
There are homolytic photoinitiators that split and generate two types of radicals, and initiators that change to active species by radiation and the active species generate radicals by abstracting hydrogen from a hydrogen donor. In addition, there are also initiators that form free radical generating species by being complexed with the photosensitizer, and initiators that generate radicals in the presence of the photosensitizer. Both types can be used. If UV sensitivity is desired, as in direct transmission imaging with UV light, suitable photoinitiators include α-alkoxyphenyl ketones, O-acetylated-
α-Oxyminoketones, polycyclic quinones, benzophenones and substituted benzophenones, xanthones, thioxanthones; chlorosulfonyl and chloromethyl polynuclear aromatic compounds, chlorosulfonyl and chloromethyl heterocyclic compounds, chlorosulfonyl and chloromethyl Halogenated compounds such as benzophenones and fluorenones, haloalkanes, α-halo-α-phenylacetophenones; photoreducible dye reducing agents redox coupling agents, halogenated paraffins (eg brominated or chlorinated paraffins ), And benzoin alkyl ethers.

Specific photoinitiators useful in the present invention include α-alkoxyketones, α, α-dialkoxyketones, benzophenones, xanthans, chloroxanthanones, chloromethylxanthanones, chlorosulfonylxanthanones, Thioxanthanone, chloroxanthanone, chloromethylthioxanthanone, chlorosulfonylthioxanthanone, chloromethylnaphthalene, chlorosulfonylnaphthalene, chloromethylanthracene, chlorosulfonylanthracene, chloromethylbenzoxazole, chloromethylbenzothiazole, chloromethyl Benzimidazole, chlorosulfonylbenzoxazole, chlorosulfonylbenzothiazole, chlorosulfonylbenzimidazole, chloromethylquinoline, chlorosulfonylquinoline, chloro Methylbenzophenone,
Chlorosulfonylbenzophenone, chloromethylfluorenone, chlorosulfonylfluorenone, carbon tetrabromide,
Benzoin methyl ether, benzoin ethyl ether, decyl chloride, decylamine, methylene blue
/ Ascorbic acid, chlorinated aliphatic hydrocarbons, and combinations thereof. The photosensitivity between these compounds can be varied by adding substituents that generate radicals when these compounds are exposed to the desired radiation wavelength.

Particularly useful as photoinitiators in the present invention are US Pat. Nos. 5,112,752; 5,100,755; 5,05.
No. 7,393; No. 4,865,942; No. 4,842,980; No. 4,800,146
Nos. 4,772,530 and 4,772,541 are cationic dye-borate anion complexes as disclosed in US Pat. When used as a photoinitiator in the present invention, the above cationic dye-borate anion complex is typically up to about 1 wt% based on the weight of the photopolymerizable or crosslinkable species in the photocurable composition. Use in quantity. Even more typically, the cationic dye-borate anion complex will have about 0.2 to about
Used in an amount of 0.5% by weight. Although the above cationic dye-borate anion complex can be used alone as the photoinitiator, preference is given to using the complex in combination with an autooxidant. Autooxidants are compounds that can consume oxygen in the free radical chain process. Useful auto-oxidants are N, N-dialkylanilines.

Examples of N, N-dialkylanilines are dialkylanilines substituted one or more in the ortho-, meta- or para-position by the following groups: methyl,
Ethyl, isopropyl, t-butyl, 3,4-tetramethylene, phenyl, trifluoromethyl, acetyl, ethoxycarbonyl, carboxy, carboxylate, trimethylsilylmethyl, trimethylsilyl, triethylsilyl, trimethylgermanyl, triethylgermanyl, trimethylstannyl , Triethylstannyl, n-butoxy,
n-pentyloxy, phenoxy, hydroxy, acetyl-
Oxy, methylthio, ethylthio, isopropylthio,
Thio- (mercapto-), acetylthio, fluoro, chloro, bromo and iodo. Representative examples of N, N-dialkylanilines useful in the present invention include 4-cyano-N, N-dimethylaniline, 4-acetyl-N, N-dimethylaniline, 4
-Bromo-N, N-dimethylaniline, ethyl 4- (N, N-dimethylamino) benzoate, 3-chloro-N, N-dimethylaniline, 4-chloro-N, N-dimethylaniline, 3-ethoxy-N , N-
Dimethylaniline, 4-fluoro-N, N-dimethylaniline, 4-methyl-N, N-dimethylaniline, 4-ethoxy-N, N-
Dimethylaniline, N, N-dimethylaniline, N, N-dimethylthioanisidine, 4-amino-N, N-dimethylaniline, 3
-Hydroxy-N, N-dimethylaniline, N, N, N ', N'-tetramethyl-1,4-dianiline, 4-acetamido-N, N-dimethylaniline, 2,6-diisopropyl-N, N- Dimethylaniline, 2,6-diethyl-N, N-dimethylaniline, N, N, 2,4,6-
Pentamethylaniline (PMA) and pt-butyl-N, N-dimethylaniline.

According to one embodiment of the present invention, the photocurable composition used in the microcapsules contains a dye borate photoinitiator and a disulfide coinitiator. Examples of useful disulfides are described in US Pat. No. 5,230,982. According to one embodiment of the present invention, the microcapsules are in three sets, each with red light,
Provided is a full color imaging system containing cyan, magenta and yellow color formers which are respectively sensitive to green and blue light. For good color balance, those visible-light-sensitive microcapsules are light-sensitive (λ max) at about 450 nm, 540 nm and 650 nm, respectively. Such systems are useful in visible light sources in direct transmission or reflection imaging. Such materials are useful in forming contact prints, projection prints on color photographic slides, or in digital printing. Also,
These materials are also useful in electronic imaging using laser or pencil light sources of suitable wavelength. Since digital imaging systems do not require the use of visible light, the photosensitivity can extend to UV and IR. Therefore, the photosensitivity is IR
And / or extend the absorption spectrum of the photoinitiator up to UV and avoid cross talk.

Developer materials used in carbonless paper technology are useful in the present invention. Specific examples include clay minerals such as acidic clay, activated clay, attapulgite, etc .; organic acids such as tannic acid, gallic acid, propyl gallate, etc .; phenol-formaldehyde resin, phenol acetylene condensation resin, at least one Acid polymers such as condensates of organic carboxylic acids having hydroxy groups with formaldehyde; zinc salicylate, tin salicylate, zinc 2-hydroxynaphthoate, 3,5-
Metal salts of aromatic carboxylic acids such as zinc di-t-butylsalicylate, zinc 3,5-di- (a-methoxybenzyl) salicylate or derivatives thereof; zinc modification as disclosed in US Pat. No. 3,732,120 Oil-soluble metal salts of phenol-formaldehyde novolac resins such as oil-soluble phenol-formaldehyde resins (e.g., U.S. Pat.
35 and 3,732,120), zinc carbonate, and mixtures thereof. The particle size of the developer material is important for obtaining high quality images. The developer particles are about 0.2 to 3 μm (0.2 to 3 μm).
3 micron) range, preferably about 0.5-1.5 μm (0.5-1.
Should be in the 5 micron range. Polyethylene oxide, polyvinyl alcohol, polyacrylamide,
Suitable binders such as acrylic latex, neoprene emulsions, polystyrene emulsions, and nitrile emulsions can be mixed with the developers and microcapsules described above, typically in an amount of about 1-8% by weight, to prepare coating compositions. .

The microcapsules and the developer are mixed,
When used in one layer or wet coated in successive layers to form a self-contained system, the developer material is
A substance having excellent compatibility with the microcapsule slurry solution is preferable. Many substances, such as zinc salicylate and certain phenolic resin preparations, contain MF
It has marginal or poor compatibility with the microcapsule preparations, leading to aggregation which is believed to be based on the incompatibility in the emulsifier used to prepare the microcapsules and in the developers. This problem manifests itself as an increase in solution viscosity, microcapsule wall instability, or both. Microcapsules can become completely disintegrated by complete destruction or disintegration of the walls.
This problem is believed to be caused by the presence of water-soluble acid salts in the developer solution. By modifying the acid salt to make it water-insoluble, the developer can be made compatible with the MF microcapsules. A preferred developer with good stability is Schenectaday International (Sc
henectady International) phenolic resin HRJ-4250 solution.

Microencapsulation can be carried out by various known methods such as coacervation, interfacial polymerization, polymerization of one or more monomers in oil, and various melting, dispersing and cooling methods. In one embodiment of the invention, the internal phase is in a urea-formaldehyde wall former, in particular a urea-resorcinol-formaldehyde wall former in which resorcinol is added to the wall former to improve its lipophilicity. Encapsulate. Other hydrophilic wall forming materials that may also be useful in the present invention include:
Gelatin (see U.S. Pat.Nos. 2,730,456 and 2,800,457 to Green et al.), Gum arabic, polyvinyl alcohol, carboxymethylcellulose, resorcinol-formaldehyde (U.S. Pat.
3,755,190), isocyanate (see U.S. Pat.No. 3,914,511 to Vassiliades), polyurethane (Kir
U.S. Pat.No. 3,796,669 to Itani et al.), melamine-formaldehyde resin and hydroxypropyl cellulose, urea-formaldehyde wall former, especially urea-resorcinol-formaldehyde wall former (lipophilic, by adding resorcinol. Improving (US Patent No. 4,001,140 to Foris et al .;
Nos. 4,087,376 and 4,089,802), melamine-formaldehyde resin and hydroxypropyl cellulose (S
U.S. Pat. No. 4,025,455 to Hackle). To the extent necessary for a complete disclosure of these wall forming materials, each of the above U.S. patents is incorporated by reference. Melamine-formaldehyde capsules are especially useful. In the present invention, it is desirable to prepare a preliminary wall when preparing the microcapsules. See US Pat. No. 4,962,010 for a particularly preferred encapsulation using pectin and sulfonated polystyrene as a system modifier. However, the preparation of preliminary walls is known and the use of large amounts of polyisocyanate precursors is desirable. The capsule size should be chosen to minimize light attenuation.

The average size of the capsules used in the present invention can vary over a wide range but is generally about 1
The range is -25 μm (1-25 microns). The general trend is that the image resolution improves as the capsule size decreases, but if the capsule size is too small, the capsule may not move properly within the support and the support may May block from exposure. In addition, there is a possibility that the microcapsules may not be broken when pressed. From these points, the preferred average capsule size range is about 1-15 μm (1-15 microns), especially about 1-10 μm.
It was found to be m (1-10 microns). In a preferred embodiment of the invention, the imaging system is a seal.
Type self-contained imaging system. As used herein, the term "seal-type" refers to a seal designed as a non-transitory seal that results in destruction of the imaging assembly when the seal is destroyed. This sealed format is advantageous as it prevents the developer substances and chemicals in the microcapsules from adhering to humans during handling, and depending on the nature of the support oxygen can penetrate into the photocurable substance. Can also be prevented to improve film speed and image stability.

To ensure that the imaging system effectively seals between the supports, a subbing layer is used between one of the supports and the imaging layer and an adhesive is imaged with the other support. Use between layers. Due to optical transparency, a subbing layer is typically used between the transparent support and the imaging layer. (The term "imaging layer" refers to a mixed layer of microcapsules and a developer, or a combination of microcapsule layers and a developer layer). However, which support will accept the subbing layer, and further which support will accept the adhesive,
It is a function of which support is coated with the wet imaging layer composition and which support is coated and assembled with the dried imaging layer. The support coated with the imaging layer composition, which is typically a transparent support, will comprise a subbing layer and the opaque support will accept the adhesive. In a preferred embodiment of the invention, the subbing layer is available from Eastman Chemical Company.
AQ polymers, such as hydroxy groups that react with and bind to microcapsules, such as partially hydrolyzed polyesters and sulfonated polyesters of aromatic acids with aliphatic or cycloaliphatic alcohols, such as AQ38 and AQ55. It is formed from a compound containing various chemical components. Also useful polymers are polyethylene oxide, especially AQUAZOL. The subbing layer is
It can be applied with a coating amount (dry weight) of about 1 to 4 g / cm ² . Although preferred, the subbing layers 16 and 18 are not necessary when the developer layer is coated on a transparent film.

One method useful for improving media stability is to condition the developer and microcapsule layers at a relative humidity of about 45-80%, preferably about 60%.
Most preferably, the subbing layer is about 2% at about 60% RH.
Condition at ambient temperature for ~ 12 hours or more. This conditioning has a beneficial effect on image retention and photographic speed. Adhesive materials useful in assembling the imaging units of this invention have good adhesion and may be formulated to improve tack by the addition of tackifying resins or other chemical additives. It can be selected from the general group of "modified acrylics". Useful adhesives should be designed to have high initial adhesion and adhesion to plastic substrates such as polyester. Effective glue is
It must have the ability to flow rapidly for lamination to a porous material (imaging layer) and yet be inert to the imaging layer. Preferably, the adhesive is transparent or translucent, and most preferably remains transparent even after exposure to the radiation and pressure necessary to imagewise expose the imaging assembly to destroy the microcapsules. Is a transparent adhesive. High strength adhesives useful in the present invention are 3M film label stock adhesives; preferred is "inert" for good imaging.
Is a 3M # 300 and # 310 adhesive composition that is stable and useful when applied in an amount of about 10 to 30 g / cm ² . Other examples of adhesives useful in the present invention are Ashland
Aerosett 2177, both commercially available from Chemical Company
Or PD available from Aerosett 2550, HB Fuller
Water-based adhesives such as 0681, AP 6903 and W 3320, or solvent-based adhesives such as PS 508 commercially available from Ashland Chemical Company. These adhesives can be used separately or in combination. The amount of adhesive will vary depending on the nature of the adhesive and the support.

When the microcapsules and the developer are coated in separate layers on separate supports, spacers or antiblocking agents may be used to improve media stability and thereby prolong the shelf life of the imaging system. . If the microcapsule layer and the developer layer remain in intimate contact with each other after development, the darkening of the image will occur in some cases due to the continuous reaction between the imageable substance of the broken microcapsules and the developer substance. Spacers can be used if this is a problem. Typically, useful spacers are particles with high shatter resistance such as calcium carbonate, glass microspheres, mineral particles such as ceramic particles. Examples of such materials have a crush resistance of 10,000 psi (703 kg / cm ² ) and a particle size of about 35 μm (35 microns) and contain about 90% “floating bodies” (low density particles). 560 / 10,000 glass microspheres from 3M; zeeospheres from Zeeosphere Industries, eg Zeosphere grade 200 and about 10 μm with average particle size of about 5 μm (5 microns).
Zeosphere 600 with an average particle size of (10 microns);
And calcium carbonate having a particle size of about 1 μm (1 micron). These spacers may be incorporated in the developer layer or in the microcapsule layer. Spacers are typically used in amounts of about 1-10% based on microcapsules.

In some cases it may also be desirable to coat the developer layer with an antiblocking agent. The antiblocking agent is coated on the developer layer to prevent the developer layer from sticking to the microcapsule layer, but does not reject the acceptance of the color precursor into the color developer to form an image with good density. It is a high-quality material. Typical examples of useful antiblocking agents are neoprene emulsions from DuPont; Morton International.
Is a polystyrene emulsion from LITERON (L
ytron) GA-5705; and Hycar-like elastomeric material which is a nitrile emulsion from BF Goodrich. Self-contained when the microcapsule layer and developer layer are not in continuous bond with each other, such as when the developer is coated on one support and the microcapsules on another. The ends of the assembly may be joined using any conventional means used to seal polymeric materials such as polyethylene terephthalate. For example, the films can be sealed with an adhesive, heat sealed together, or sealed by any other method. Preferably, the PET is sealed using a heat sealing method such as a heat knife. Although the seal has been described as being distal, it will be understood that the seal can also be inserted from the end, for example to the border, so long as it is inserted between the imaging chemical and the user. .

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is illustrated in more detail by the following non-limiting examples. Example 1 Laboratory Capsule Preparation as a Model 1. In a stainless steel beaker, add 110 g of water and 4.5
g sodium salt of polyvinylbenzene sulfonic acid (VERSA) was weighed. 2. The beaker was fixed on a hot plate under the overhead mixer. A 6-blade 45 ° pitch turbine impeller was used on the mixer. 3. After mixing well, 4.0 g pectin (polygalacturonic acid methyl ester) was added slowly into the beaker. The mixture was stirred at room temperature for 2 hours (800-1200 rp
m). Four. The pH was adjusted to 6.0 with 2% sodium hydroxide. Five. Raise the mixer to 3000 rpm to bring the internal phase to 10-15
Added in seconds. The emulsification was continued for 10 minutes. The magenta and yellow precursor phases are emulsified at 25-30 ° C and the cyan phase is 45-
It was emulsified at 50 ° C (oil) and 25-30 ° C (water). 6. At the beginning of the emulsification, the hot plate was raised so that heating continued throughout the emulsification. After 20 minutes, the mixing speed was reduced to 2000 rpm and the melamine-formaldehyde prepolymer solution was added slowly. This prepolymer contains 6.5 g of formaldehyde solution (37
%) Was added to a 3.9 g melamine dispersion in 44 g water. After stirring for 1 hour at room temperature, the pH was adjusted to 8.5 with 5% sodium carbonate and then heated to 62 ° C until the solution became clear (30 minutes). 8. The pH was adjusted to 6.0 with 5% phosphoric acid. afterwards,
Cover the beaker with foil and place in a water bath to adjust the preparation temperature to 75 ° C.
I chose When 75 ° C is reached, the heat plate is adjusted to maintain this temperature for a 2 hour cure time, during which
The capsule wall was formed. 9. After curing, the mixing speed was reduced to 1800 rpm, formaldehyde scavenger solution (7.7 g urea and 7.0 g water) was added and the solution was cured for an additional 40 minutes. After a holding time of 10.40 minutes, reduce the mixer rpm to 1100 and
The pH was adjusted to 9.5 with 0% NaOH solution and then stirred at room temperature overnight at 500 rpm.

Three batches of microcapsules were prepared as described above for total color imaging sheets using the three internal phase compositions described below. Yellow capsule Internal phase (420 nm) TMPTA 163.6 g Photoinitiator 0.80 g Bis-2,2 'benzothiazole disulfide 0.55 g 2,6-Diisopropyldimethylaniline (DIDMA) 0.82 g CP 269 (yellow dye precursor from Hilton Davis) Body) 16.0 g Desmodur N-100 (Bayer-Bullet polyisocyanate resin) 13.0 9 g Magenta capsule internal phase (550 nm) TMPTA 147.3 g DPHPA 16.3 g Photoinitiator 0.47 g Bis-2,2 'benzothiazole disulfide 0.55 g 2,6-Diisopropyldimethylaniline 1.09 g CP 164 (magenta color precursor from Hilton Davis Chemical) 25.3 g Desmodur N-100 (Bayer-Bullet polyisocyanate resin) 13.09 g Cyan capsule internal phase (650 nm) TMPTA 114.50 g DPHPA 49.10 g Photoinitiator 0.85 g Bis-2,2 'benzothiazole disulfide 0.55 g 2,6-Diisopropyldimethylaniline 1.09 g CP 270 (Yamada Chemical Company of Japan La cyan precursor) 6 g

The microcapsules prepared as described above can be mixed in the following dry percent ratios to prepare the following coating composition: Cyan capsule 38% Magenta capsule 32% Yellow capsule 30% Typical coating composition Articles can be coated on an opaque PET support (Melinex) with a dry coating amount of 17 g / m ² . Such compositions include the following components: Cyliths 4.94 g (29%) Phenolic resin (HRJ 4542 from Schenectady Chemical) 11.54 g (68%) Polyvinyl alcohol (airvol grade from Air Products) 205) 0.26 g (1.5%) Sequrez 755 (binder) 0.26 g (1.5%) In order to produce a film unit, a developer-coated film is combined in face-to-face relationship with a microcapsule-coated support and two The ends of the support can be sealed with Ashland PS 508 adhesive.

Example 2 The following coating composition can be prepared and coated on a PET support: Cyan capsule (Example 1) 36 g Magenta capsule (Example 1) 30 g Yellow capsule (Example 1) 34 g Dow binder 10 g HRJ 4542 developer (Schenectady Chemical Co.) 90 g PVA (airvol grade 205 from Air Products Co.) 10 g In order to produce a film according to the invention, a sheet coated as described above The Ashland PS 508
Combine with adhesive coated Melinex 6295 film and seal to form a film unit.

While the present invention has been described in detail by reference to its preferred embodiments, it will be apparent that modifications and variations are possible without departing from the scope of the invention as defined in the claims. Would be [a brief description of the drawing]

FIG. 1 illustrates a photosensitive material according to one embodiment of the present invention.

1A shows a three-layer structure of the support 20 of FIG.

Figure 2 Figure 1 after exposure and destruction of microcapsules 14
Figure 3 shows a self-contained imaging system of.

3 and 4 illustrate a further embodiment in which a developer is used in layer 16 ′ and microcapsules are used in layer 14 ′ instead of the single layer of FIGS. 1 and 2.

FIG. 5 illustrates a further embodiment of the photosensitive material according to the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References Japanese Patent Laid-Open No. 10-301297 (JP, A) Special Table 10-504658 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03F 7/00-7/42

Claims (14)

(57) [Claims] 1. A photosensitive material comprising an opaque support and a photosensitive microcapsule layer, the microcapsules including an internal phase containing a photosensitive composition and a color precursor, the photosensitive material comprising: Upon imagewise exposure to actinic radiation and destruction of the microcapsules in the presence of a developer material, the color precursors react imagewise with the developer material to form a color image, the support A photosensitive material characterized in that the body is a highly opaque laminate having a black or brown film laminated between a pair of white pigmented films. 2. The photosensitive material according to claim 1, wherein the photosensitive material is a self-contained image forming system. 3. The self-contained image forming system is a seal type self-contained image forming system further comprising a transparent support, and the photosensitive microcapsules and the developer are inserted between the respective supports. The photosensitive material according to claim 2. 4. The photosensitive material of claim 3, wherein the sealable self-contained imaging system further comprises an adhesive. 5. The photosensitive material of claim 3, wherein the sealable self-contained imaging system further comprises a subbing layer between the transparent support and the opaque support. 6. The photosensitive material according to claim 3 , wherein the transparent support is a transparent polyethylene terephthalate film. 7. A photosensitive microcapsule layer containing a transparent support, an opaque support, an internal phase containing a photosensitive composition and a color precursor interposed between these supports, and within the photosensitive microcapsule layer. Alternatively, the microcapsules are imagewise exposed to actinic radiation, including a developer present in a separate layer interposed between the supports, to destroy the microcapsules and cause the color precursors to Characterized in that it is released from the capsule and reacts with the developer material to form a color image, the opaque support being a highly opaque laminate of black or brown film laminated between two white pigmented films. Photosensitive material. 8. The photosensitive material according to claim 1, wherein the black or brown film is a black film containing carbon black. 9. The photosensitive material of claim 1 wherein the black or brown film comprises a magnetic recording pigment such that the photosensitive material can be used to magnetically record information. 10. The sealable self-contained image forming system comprises:
The photosensitive material according to claim 7, further comprising an adhesive. 11. The photosensitive material of claim 7, wherein the sealable self-contained imaging element further comprises a subbing layer between the transparent support and the opaque support. 12. The photosensitive material according to claim 7, wherein the transparent support is a transparent polyethylene terephthalate film. 13. The photosensitive material according to claim 7, wherein the black or brown film is a film containing carbon black. 14. The photosensitive material of claim 7 wherein said black or brown film comprises a magnetic recording pigment such that said photosensitive material can be used to magnetically record information.